Leonardo da Vinci proposed a double hull to help a damaged vessel remain afloat.
His ship drawings include the idea of separating the outer hull from an inner hull, creating a protective space between them. If the outside plating were breached, the inner structure could reduce the amount of water entering the vessel. The principle resembles the double hulls later used in some ships and boats for added protection and buoyancy.
Leonardo’s proposal was part of his wider study of naval engineering, canals, and military technology. It should not be confused with a double-ended ship or with internal ballast. A double hull is specifically a second watertight layer or shell, although historical designs do not always match modern naval terminology exactly.
Modern double-hull construction became especially important for tankers after environmental and maritime-safety reforms. Leonardo did not build a modern oil tanker, and his drawing should be understood as an early conceptual proposal rather than a tested shipbuilding standard. Its significance is the recognition that layered structure could improve survivability after damage.